In addition to surfactants, polymers are utilized as soil detachment-promoting additives in laundry detergents. These polymers may be suitable for use in the laundry liquor as dispersants of soil pigments such as clay minerals or soot, and/or as additives which prevent the reattachment of soil to the fabric being laundered. However, these polymeric dispersants may be ineffective in the removal of hydrophobic soil from textiles, particularly when they are utilized under low temperature washing conditions.
The amphiphilic graft copolymers described in USPN 2009/0005288A1 and 2009/0005287A1 are particularly suited for the removal of hydrophobic soil from fabric in the wash liquor. Consequently, it would be very desirable to provide a granular laundry detergent composition comprising such polymers. However, previous attempts to incorporate amphiphilic graft copolymers have led to the discoloration of the resulting granular detergent compositions.
Consumers may associate the cleaning power of a granular detergent composition with its appearance. For this reason, it may be disadvantageous to market a detergent in which some or all of the granules are discolored. Yet it can be costly to remove and/or mask the discolored granules through additional processing steps and/or through the addition of further components to the detergent (such as titanium dioxide for example). The additional cost can be undesirable for both the detergent manufacturer and consumer.
Thus there is currently a need to provide a granular detergent composition that is suited for removing hydrophobic soil and that has a consumer acceptable appearance. Moreover there is a need for a method of making such a granular detergent composition without incurring substantial cost to mask any discoloration. There is particularly a need for a method of making a granular detergent composition in which no substantial discoloration of the amphiphilic polymers occurs.